# -*- coding: utf-8 -*-

import base64
import hashlib
import hmac
import math
import struct
import time


def cal_google_code(secret_key):
    # secret key 的长度必须是 8 的倍数。所以如果 secret key 不符合要求，需要在后面补上相应个数的 "="
    secret_key_len = len(secret_key)
    secret_key_pad_len = math.ceil(secret_key_len / 8) * 8 - secret_key_len
    secret_key = secret_key + "=" * secret_key_pad_len

    duration_input = int(time.time()) // 30
    key = base64.b32decode(secret_key)
    msg = struct.pack(">Q", duration_input)
    google_code = hmac.new(key, msg, hashlib.sha1).digest()
    o = google_code[19] & 15
    google_code = str((struct.unpack(">I", google_code[o:o+4])[0] & 0x7fffffff) % 1000000)

    # 生成的验证码未必是 6 位，注意要在前面补 0
    if len(google_code) == 5:  # Only if length of the code is 5, a zero will be added at the beginning of the code.
        google_code = '0' + google_code
    return google_code

print(cal_google_code('GLJROBOT6HVWV3P55KTF2AQERQ'),end="")